With the rapid development of the 3C hi-tech industry, the 3C electronic products present advanced and novel designs persistently. However, the heat-dissipating problems also arise with the promoted efficacy of the electronic products. Therefore, most of the electronic products are equipped with heat-dissipating modules to drain the heat generated inside the electronic products.
Exemplified by the computer, if the heat generated by the electronic elements cannot be drained, the temperature will rise, which induces the computer to crash or even stop operating. Therefore, a general PC always has heat-dissipating fins and electric fans. The heat-dissipating fins are made of multiple metallic plates and used to increase heat-dissipating area. In addition to increasing heat-dissipating area, an electric fan, which generates an enforced air stream to blow away the heat, is also needed. However, the heat-dissipating efficiency of the aforementioned heat-dissipating fins is inferior, which results in that heat cannot be drained rapidly. Therefore, an advanced technology—thermoduct—had been developed.
The thermoduct is an enclosed metallic tube containing an appropriate amount of working fluid, such as pure water or acetone. The working fluid is in vacuum state, and when the heated end of the thermoduct absorbs heat, the working fluid is evaporated, and the vapor of the working fluid will flow to the cooling end of the thermoduct where the pressure is lower. The vapor of the working fluid will then be condensed and releases latent heat in the cooling end. The condensed working fluid will flow back to the heated end via capillarity. Heat dissipation is therefore achieved via the cycling of evaporation and condensation.
The speed of the vapor is much higher than that of the liquid in the thermoduct; therefore, the backflow speed of the liquid working fluid is a critical factor in the heat-dissipating efficiency. Conventional thermoducts utilize the capillary texture of engraved trenches or metallic nets thereinside to speed up the backflow liquid working fluid. Further, cupric powder can also be sintered to the inner wall of the metallic tube to form a layer of porous material, which can enhance the capillary effect and helps the liquid working fluid flow back.
Taiwan Patent Publication No. 572250 discloses a thermoduct adopting cupric powder as capillary texture, and the fabrication process thereof is shown in FIG. 1A˜FIG. 1C Prior Art. A tube 100 has an open end 102 and a closed end 104, as shown in FIG. 1A Prior Art. A cupric rod 110 is inserted through the open end 102 into the tube 100, and then, cupric powder 120 is filled into the gap between the cupric rod 110 and the inner wall of the tube 100. The cupric powder 120 is sintered to adhere to the inner wall of the tube 100, as shown in FIG. 3B Prior Art, and next, the cupric rod 110 is drawn out to form a hollow portion 106, as shown in FIG. 3C Prior Art. The tube 100 is then evacuated, and working fluid (not shown in the drawing) is filled thereinto, and lastly, the open end 102 is sealed. Via the cupric powder 120, heat can be conducted rapidly, and a better heat-dissipating effect can be achieved.
However, in the fabrication process of the abovementioned thermoduct, a portion of the cupric powder 120 will be drawn out also in the step of drawing out the cupric rod 110, and thus, the amount of the cupric powder 120 sintered to the inner wall of the tube 100 is lessened. Further, the fabrication of the abovementioned thermoduct is uneasy, manpower-consuming, time-consuming, and expensive.